Group 14 HTML to XHTML How to:
Jason McCreary (how to leader)
Toddrick Manning

The differences Between HTML 4 and XHTML


HTML is set to be the next step in the evolution of HTML. XHTML or "eXtensible Hyper Text Mark-up Language" is very similar to the latest version of HTML (4.0) To quote Jennifer Kyrnin of About.com "XHTML is HTML 4.0 Written in XML Format". She also writes "XML is an extensible markup language that was developed to retain the flexibility and power of HTML while reducing most of the complexity. XHTML combines the flexibility of HTML with the extensibility of XML." The "extensible" part means it can be "extended" with the addition of new tags.

Some of the Diffrences Between HTML 4 and XHTML follow.

Tags:

All tags must now be closed

<br> becomes <br />
<td> becomes <td>...</td >
<tr> becomes <tr>...</tr>
<p>... becomes <p>...</p>
<a> becomes <a /> or <a>...</a>
<html> becomes <html xmlns="http://www.w3.org/1999/xhtml">

Tags must not have missing elements

<img> tags must include alt="image description" to be correct

Tags cannot rely on defaults

correct:
<table border="0" cellpadding="0" cellspacing="0" width="88%">
Incorrect:
<table width="88%">

Tags cannot over lap

<u><b>hello</u></b> is incorrect
<u><b>hello</b></u> is correct

All tag attributes must be in quotes

<script type="text/javascript">

Tags must be lower case



Elements (required)

Documents (pages) must be well formed. example: elements cannot overlap.
There are no explicit values of any kind
They must contain a DOCTYPE statement at the top